Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 011432

Area Forecast Discussion
National Weather Service Burlington VT
932 AM EST Wed Dec 1 2021

Other than lingering snow showers over the northern mountains early
this morning, today will be dry with highs mainly in the 30s. Our
next system moves in Thursday morning, bringing rain and summit snow
through the daylight hours. This will change back to all snow
Thursday night, with some light accumulations possible over the
higher summits.


As of 932 AM EST Wednesday...Quick update made to the forecast
to account for some heavy banded snow showers the developed
across central VT. NWS employee noted reduced visibility on I-89
in Waterbury and Middlesex and BTV just recently dropped to
1/4SM. This activity should move east and dissipate within the
next hour or 2 with quiet conditions still expected thereafter.

Previous discussion...Scattered snow showers/light mountain
snow will continue to wind down this morning as a frontal
passage brings drier air to the region. Any additional
accumulation will be pretty minimal. Otherwise, clouds will
linger through the morning before we start to see some sun
peeking through this afternoon. Winds will be on the breezy side
as daytime heating combined with cooling aloft result in good
mixing. Highs will mainly be in the lower to mid 30s, with a few
of the colder spots remaining in the upper 20s.

Our next system approaches tonight as low pressure currently over
the Canadian Prairie Provinces moves southeastward toward the
northern Great Lakes overnight. Flow will turn to the southwest
ahead of this system, and the resultant warm air advection and
favorable jet dynamics will allow precipitation to develop late from
west to east tonight into early Thursday morning. Temperatures will
fall early but then will hold steady or even warm slightly
overnight, especially in the St Lawrence and Champlain Valleys.
Therefore precipitation will start out as snow but will mix with
and/or change over to rain by daybreak at lower elevations.
Precipitation will become more widespread on Thursday as the low
slides eastward across Ontario and Quebec. Warming will continue
through the day on a 850 mb 50+kt southwesterly jet, allowing snow
to change over to rain everywhere but the highest summits with
temperatures reaching into the upper 30s/lower 40s. As is usually
the case, surface temperatures will be slowest to warm above
freezing east of the Green Mountains, so some pockets of freezing
rain will be possible in sheltered locations, until warmer air is
able to make it all the way to the ground. The warming aloft and
steady precipitation will help to limit mixing of the aforementioned
jet down to the surface, but still anticipate a gusty day on
Thursday, especially in the Champlain Valley due to channeling and
on the northern downslope side of the Adirondacks.


As of 255 AM EST Wednesday...An arctic cold front will move through
the North Country Thursday night and we will see lingering
precipitation transition to all snow as temperatures aloft and at
the surface quickly cool. As the low level jet exits eastward, we
should see the radar fill in as any downsloping conditions seen on
the lee side of the Adirondack and Green Mountains come to an end.
Minor snow accumulations are expected Thursday night but most
locations will see precipitation come to an end around midnight as
the front also exits eastward. The stages are being set for a
potential flash freeze event Thursday night as temperatures between
midnight and 5 AM are expected to drop well below freezing very
quickly. Given many places will see rain during the day on Thursday,
black ice is very possible and could lead to a slippery commute
Friday morning.

As is typical this time of the year, with northwest flow lingering
across the North Country, we will see some upslope snow showers
continue across the western slopes of the Green and Adirondack
Mountains through much of the day on Friday. Decreasing moisture
will be a limiting factor to snowfall totals but some of the higher
slopes could see 1-3 inches of fluff.

Gusty winds will continue through the overnight hours on Thursday
but won`t be of the same magnitude as seen during the daylight hours
as winds veer to the west/northwest and we lose the channeled
southerly flow. Winds are expected to strengthen during the daylight
hours on Friday as we will be mixing deeply to 850 mb. Winds will
abate Friday night but winds in the 10-15 mph range will likely
continue. These winds will lead to very cold wind chills through the
forecast period with wind chills between 10 and 20 degrees through
the day on Friday.


As of 255 AM EST Wednesday...A very active pattern is setting up for
this upcoming weekend and the first half of next week. An active
longwave pattern will be reinforced by an arctic outbreak which will
allow several amplified upper level troughs to sweep through the
region. The first disturbance will push through the region on
Saturday as a clipper- like low will move through the North Country.
Taking a look at the snow squall parameter, there are some
indications we could see some convective snow showers across the
region. However, true snow squalls don`t appear very favorable at
this time as temperatures will already below freezing which will
mitigate any flash freeze potential and the lack of any surface
boundary will prevent storms from getting any organizational
development. The NAM is spitting out 100-200 J/kg of CAPE which
could produce some convective snow showers and with background wind
fields already in the 10-20 mph range, it will feel "squally" out
there. Snowfall accumulations will be tough as convective showers
will yield localized maxima but it looks like a decent bet most
places should see accumulating snow on Saturday.

The next system will take aim at the North Country on Monday. Models
are coming into good agreement that we will see a maturing surface
cyclone move across the Great Lakes and into southern Quebec during
the day on Monday. With the low expected to pass to our west, we are
setting the stage for another mixed precipitation event with a burst
of snow Monday morning associated with a weak warm front, followed
by rain and gusty winds and then ultimately changing into an upslope
snow event Monday night into Tuesday. A third system looks to impact
the region on Wednesday and it appears the storm track will be
similar to the one Monday with mixed precipitation and gusty winds


Through 12Z Thursday...Light snow showers will gradually end
from west to east through 15z as a cold front pushes eastward
across the region. Conditions currently a mix of MVFR and VFR,
with perhaps some highly localized IFR possible in snow showers,
mainly in the higher terrain. Once snow ends, ceilings will lift
to AOA 5000 ft by 18z and remain so through 03z. Then clouds
thicken and lower once again ahead of the next system, dropping
to MVFR at KMSS and KSLK by 08z. Precipitation will mainly hold
off until just after this TAF period. South to southwest winds
will turn to the west behind the front, mainly 5 to 10 kt with
gusts up to 20 kt possible. Winds become light after 00z
tonight, but a low-level jet will result in LLWS at all
terminals after 08z.


Thursday: Mainly MVFR, with local IFR possible. Likely SHRA.
Thursday Night: Mainly MVFR, with areas VFR possible. Chance
SHRA, Chance SHSN.
Friday: Mainly VFR, with local MVFR possible. Slight chance SHSN.
Friday Night: VFR. Slight chance SHSN.
Saturday: Mainly VFR, with local MVFR possible. Chance SHSN.
Saturday Night: Mainly VFR, with local MVFR possible. NO SIG WX.
Sunday: VFR. NO SIG WX.




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